%% introduction environment is base on elegantbook.cls
%% start of file `elegantbook.cls'.
%% Copyright 2013-2019 ElegantLaTeX (elegantlatex2e@gmail.com)
%%
%% This work may be distributed and/or modified freely
%% available at https://github.com/ElegantLaTeX/ElegantBook
\usepackage{multicol}
\usepackage{tcolorbox}
\tcbuselibrary{most}
% list/itemize/enumerate setting
\usepackage[shortlabels]{enumitem}
\tcbset{
    introduction/.style={
        enhanced,
		breakable,
		colback=structurecolor!10,
		colframe=structurecolor,
  		fonttitle=\bfseries,
  		colbacktitle=structurecolor,
  		fontupper=\sffamily,
  		attach boxed title to top center={yshift=-3mm,yshifttext=-1mm},
  		boxrule=0pt,
  		toprule=0.5pt,
  		bottomrule=0.5pt,
  		top=8pt,
        before skip=8pt,
  		sharp corners
    },
}

\newenvironment{introduction}[1][\introductionTitle]{
\begin{tcolorbox}[introduction,title={#1}]
\begin{multicols}{2}
\begin{itemize}[label=\textcolor{structurecolor}{\scriptsize\SquareShadowBottomRight}]
}{%
\end{itemize}
\end{multicols}
\end{tcolorbox}}